This invention relates to means for severing bone pins or other elongate elements transversely without imposing twisting, racking or other forces upon the element during severing.
Heretofore, devices for shearing bone pins and other cylindrical elements have included saws, pinch-type and coaxial, manually operated shears and the like which are satisfactory for usage in some instances with the smaller diameter bone pins, but become difficult to use with the larger diameter, intramedullary bone pins frequently being used in the fixation of fractures of large bones in both the human and veterinary orthopedic medicine fields. In addition, many of the prior art devices twist, rack and otherwise distort the element being severed and frequently leave a jagged and distorted end after severing. To accommodate the various sizes of pins in use, it is necessary to have a plurality of the prior art instruments for cutting the pins to the desired length. In addition, in instances in which one end of the bone pin has already been anchored in the intramedullary zone of a bone, the prior art devices pose difficulties in holding the bone pin during severing.
One well-known prior art device comprises a rotatable pin cutter means positioned within a cutter body. The cutter body and cutter plug means are rotated by movement of handles attached to each element of the cutter. A pin is placed into a diametric passageway in the cutter plug which is aligned with an aperture in the cutter body. The elements are then manually rotated with respect to each other, severing the pin. The requirement of long handles attached to the cutter elements in order to develop sufficient force for cutting the pin makes this device cumbersome and under certain circumstances unusable when severing a bone pin positioned in the bone of a large animal. A substantial amount of working space is necessary for using this device, making it difficult to use in cutting pins in some positions.